Okay, the change in the numerical refractive index between water and
some solutions of sugar water might indeed be small, but consider the
following:
For the calibration solutions I suggested when measuring sugar in soft
drinks and juices, the strongest solution is 1.5 teaspoons sugar in one
ounce of water. That is about 22% Brix (22% w/w) sugar in water. The
refractive index of pure water is about 1.33 and for 22% Brix the
refractive index is about 1.37. This is about a 3% difference. But
many common glass formulas have a refractive index less than 1.50, for
example typical fused silica glass is about 1.47, and that is only a 10%
difference with water (difference over average times 100%). Crown glass
is 1.52 (used in many optical instruments and lenses).
Sugar syrups run from 60% to 80% sugar, and honey is often around 85%
sugar. At roughly 84% sugar the refractive index passes 1.50, and
therefore the refractive index of typical honey is higher than typical
glass and is approaching crown glass.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of curtis
osterhoudt
Sent: Tuesday, May 12, 2009 11:34 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] index of refraction
Hi, Mike,
My only reason for saying that the index of refraction for visible
light in salt/sugar/water solutions isn't dramatically higher than plain
water is that it's generally far less than a 5% change from 1.333. It's
certainly less than most glasses. I was pointing out---as you did---the
dramatic effects even a small change can have over many optical
wavelengths.
Cheers,
Curtis O.
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